"Is being gay a product of choice, preference, environment or is it caused by a mutated sex determining gene?"

None of the above. These are often given as the main guesses but they are notabily wrong and naive. A couple facts of gayness.

1) Twins share sexual preference to a greater degree than siblings share sexual preference.
2) Identical twins share sexual preference to a greater degree than fraternal twins.
3) Identical twins do not share 100% identical sexual preference.
4) The youngest son of a woman who has had several sons has a statistically significant increased chance of being homosexual.
5) This increased chance does not exist if the child is not biologically hers.

These aren't in dispute. And they tell us a lot of what the answer could be. In that it's not choice, and it's not strictly genetics. It is to some degree congenial (being established during gestation), and to some degree genetic. Because twins are more likely to share sexual orientation than siblings and they are genetically just siblings. But, identical twins don't absolutely share sexual identity, which would be a requirement if it were genetic because they would share all of their genes.

So we're likely talking about something that is genetically influenced, that happens during development in a rather complicated cascade of hormones that isn't absolute. The ability to turn off the attraction to one sex during development isn't absolute. In fact, in bonobos it's completely gone leaving the population to be completely bisexual. Attraction to generally one gender more than another isn't an exacting thing, it's actually somewhat vague and sometimes wrong. Just as gender identity is often wrong, and a large degree of inter-sexed people. The fact is, being attracted to men, is perfectly common and typical for women. So it's not as much some kind of freak mutation as a imperfect sexual dimorphism of a somewhat useful but generally unrequired non-attraction to one gender. Both non-attraction to men and non-attraction to women are common but they are generally closely tied with one's gender. Being closely rather than absolutely means that gayness exists.

If I weren't humble, I would post this to Facebook or something where people could see it. So playing Minecraft, there's a newly added end game section to the game. Where you can actually beat the thing rather than an endless sandbox. Well, to get there you can track Eyes of Ender, which are silly things that you throw into the sky that fly up and land towards the Fortress, where you might be able to get to the end part. I realized that you can just triangulate the position. After two throws at P(-32,-198) which ended at P(-22,-198) and P(-250,-1556) which ended at P(-241, -1546) I calculated the position at P(972,-198). We went there, dug around, and found the sucker at P(1070,-101). The important bit being that we found the sucker. Seriously, there's so much space in the game and I found the sucker with math. When used right, Math is like a super-power.

I admit it's a bit speculative, but really does fit the observed phenomenon well. When a god believer tells you to believe in their God. It's a bit like they are offering this figure in their heads to you, that they have come to know and love. And telling them, no, that doesn't exist, and you're wrong. Really is a kind of rejection of God (of their God in their head) and of that person. Reacting emotionally is the obvious response, whereas I've analogized it to becoming upset because I don't believe in bigfoot, but theists don't have a person relationship with bigfoot.

"Hey, do you want to go steady with my God?" -- No. Your God is fake, stupid, doesn't make any sense. Nobody should go steady with that mythological hogwash.

There's some margin between what we know and what is possible. For example if you want to think the universe is 13.6 billion years old, you're in luck that's within the margin of error for the last WMAP readings. If your religion says that the universe works by loop quantum gravity, you're in luck it very well might. If your religion says the universe is 6,000 years old, you're just wrong. That's well outside the margin of error.

About Me

I am a 32-year-old straight white college educated male who likes his odds. --
I'm a liberal atheist with a degree in Computer Science, broad interests, and ... there really should be a good 'third thing' to put here. Oh, well, I'm limiting myself to 30 seconds of thinking about it. -- Don't ever try to list things and toss in a superset like "broad interest".